[FFmpeg-user] aspect ratio changes in the middle of the stream

littlebat dashing.meng at gmail.com
Sat Sep 7 15:29:18 CEST 2013

On Fri, 06 Sep 2013 16:07:01 +0100
Tim Nicholson <nichot20 at yahoo.com> wrote:

> On 06/09/13 12:43, Carl Eugen Hoyos wrote:
> > Tim Nicholson <nichot20 <at> yahoo.com> writes:
> > 
> >> MAy broadcast .ts streams set aspect ratio on a frame by frame
> >> basis, the question is how to get ffmpeg to do the same.
> > 
> > I don't think this is possible but it is the opposite of 
> > what was asked in this thread, or am I wrong?
> > 
> No, I was being slightly simplistic/vague in my description sorry to
> confuse. I think that padding to 16:9 on a frame by frame basis is
> what is wanted, the principle is what I was after, i.e, get one filter
> (aspect, padding) to dynamically alter its parameters, frame by frame
> based upon frame rate metadata extracted from each frame.

I doubt if there is a container format or video codec can has variable
aspect in one video stream. I don't suppose the player how to treat this

Can you post a sample has variable aspect in one video stream?

I remember you record the TV program into file? I also doubt you can
get a video file own variable aspect.

Although I have not test on it. I suppose your video is all 4:3 Display
Aspect Ratio, and there is some wide screen (16:9) part is padded with
black bar on top and bottom(Letterbox), but, in fact, it is 4:3 DAR.

So, if you want treat those "Letterbox" part specially, you need cut
the video file and pick them out to do the additional treatment, then
assemble them together if necessary.

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